It is well known that when different plant lines are cross-pollinated, one can achieve in the offspring a highly desirable heterosis or hybrid vigor which advantageously provides increased yields of the desired crop.
Representative crops which have been successfully hybridized in the past include sugar beets, corn (See, U.S. Pat. No. 3,753,663 to Jones), sorghum, alfalfa (See, U.S. Pat. No. 3,570,181 to Davis), wheat, sunflowers, cotton, rice (See, U.S. Pat. No. 4,305,225 to Yuan), cucumbers, onions, carrots, and tomatoes.
It is well-recognized that cotton (plants of genus Gossypium) is an important crop which is grown in many parts of the world. While the necessary plants for hybrid cottonseed production are known and available, only limited hybrid cotton production has been carried out to date. For instance, in some parts of the world cotton plants have been emasculated by hand and the pollen has been transferred to the female parent by hand.
While the necessary cotton plants for a cytoplasmic-genetic male sterile system for hybrid cottonseed production are known and available, such system has heretofore been largely impossible to reliably implement on a commercial basis since it has proven to be a tremendous undertaking to monitor the level of hybridization in the final cottonseed product and to determine and maintain purity in the parental lines.
Heretofore, most commercially grown cotton varieties have been the broad-leafed varieties. However, it has been recognized that under some growing conditions the narrow-leafed cotton varieties (e.g., Pronto and Gumbo) may perform better. For instance, when the growing conditions are highly conducive to cotton boll rot, then the more open canopy growth habit of the cotton plants made possible with the narrow-leafed cotton varieties may be preferable. Such openness will better enable sunlight to reach the cotton bolls and for the plant to better receive an insecticide at its innermost locations. Also, studies have been conducted in the past with respect to insect visitation preferences concerning broad- and narrow-leafed cotton varieties. For a recent discussion of the effects of cotton leaf shape on yield see "Influence of Leaf Morphology on Lint Yield of Cotton-Enhancement by the Sub Okra Trait," William R. Meredith Jr., Crop Science, Vol. 24, p. 855 to 857, Sept.-Oct. 1984.
Representative prior publications which concern the formation of hybrid cottonseeds are the following:
(1) Canadian Pat. No. 668,452, "Production of Hybrid Cottonseed," Frank M. Eaton, Aug. 13, 1963.
(2) Vesta G. Meyer, "Male Sterility From Gossypium harknessii," J. of Heredity, Vol. 66, p. 23 to 27 (1975).
(3) Joseph O. Moffett, Lee S. Stith, and Charles W. Shipman, "Producing Hybrid Cotton Seed on the High Plains of Texas," Beltwide Cotton Production Research Conferences Proceedings, Atlanta, Ga., p. 90 to 92 (1977).
(4) J. B. Weaver, Jr., "Present Status of Fertility Restoration in Cytoplasmic Male-Sterile Upland Cotton," Beltwide Cotton Production Research Conferences Proceedings, Atlanta, Ga., p. 95 to 96 (1977).
(5) Joseph O. Moffett, Lee S. Stith, and Charles W. Shipman, "Producing Hybrid Cotton Seed on a Field Scale by Using Honey Bees as Pollinators," Beltwide Cotton Production Research Conferences Proceedings, Dallas, Tex., p. 77 to 79 (1978).
(6) W. R. Meredith, Jr., Vesta Meyer, B. W. Hanny, and J. C. Bailey, "Influence of Five Gossypium Species Cytoplasms on Yield, Yield Components, Fiber Properties, and Insect Resistance in Upland Cotton," Crop Science, Vol. 19, p. 647 to 650, Sept.-Oct. 1979.
(7) Richard H. Sheetz and James B. Weaver, Jr., "Pima Fertility Enhancer Factor: Inheritance and Use in Hybrid Cotton Production," Beltwide Cotton Production Research Conferences Proceedings, St. Louis, Mo., p. 82 (1980).
(8) R. H. Sheetz and J. B. Weaver, Jr., "Inheritance of a Fertility Enhancer Factor From Pima Cotton When Transferred Into Upland Cotton With Gossypium harknessii Brandegee Cytoplasm," Crop Science, Vol. 20, p. 272 to 275, Mar.-April 1980.
(9) Delbert C. Hess, "Hybrid Cotton Development," Beltwide Cotton Mechanization-Production Research Conferences Proceedings, New Orleans, La., p. 28 to 29 (1981).
(10) J. E. Quisenberry and R. E. Dilbeck, "Stormproof Boll in Upland Cotton III. Genotype-Environment Interaction and Genetic Analysis," Crop Science, Vol. 21, p. 511 to 514, July-August 1981.
(11) James B. Weaver, Jr., "Recent Significant Observations on the Development of Hybrid Cotton," Beltwide Cotton Production Research Conferences Proceedings, Las Vegas, Nev., p. 88 to 90 (1982).
(12) James B. Weaver, Jr., "Interspecific Hybrid Cotton as a Trap Crop for Boll Weevil Control," Beltwide Cotton Production Research Conferences Proceedings, Las Vegas, Nev., p. 207 to 209 (1982).
(13) Frank L. Carter, Dick D. Davis and Elbert R. Jaycox, "Effect of Planting Pattern on Cross Pollination in Hybrid NX-1 Seed Production," Beltwide Cotton Production Conferences Proceedings, Atlanta Ga., p. 130 to 131 (1984).
(14) J. B. Weaver, "Hybrid Cotton Sets a Good Weevil Trap," Progressive Farmer, August 1984.
Representative prior publications which concern to at least some degree leaf shape configurations in cotton plants are the following:
(1) J. A. Andries, J. E. Jones, L. W. Sloane, and J. G. Marshall, "Effects of Okra Leaf Shape on Boll Rot, Yield and Other Important Characters of Upland Cotton, Gossypium hirsutum L., " Crop Science, Vol. 9, p. 705 to 710, Nov.-Dec. 1969.
(2) J. A. Andries, J. E. Jones, L. W. Sloane, and J. G. Marshall, "Effects of Supra Okra Leaf Shape on Boll Rot, Yield, and Other Characters of Upland Cotton, Gossypium hirsutum L.," Crop Science, Vol. 10, p. 403 to 407, July-Aug. 1970.
(3) J. E. Jones, "Effect of Morphological Characters of Cotton on Insects and Pathogens," Beltwide Cotton Production Research Conferences Proceedings, Las Vegas, Nev., p. 88 to 92 (1972).
(4) J. E. Jones, W. D. Caldwell, M. R. Milam, and D. F. Clower, "Gumbo and Pronto: Two New Open-Canopy Varieties of Cotton," Circular No. 103, Louisiana State University, December 1976.
(5) W. D. Caldwell, D. R. Melville, A. M. Pavloff, and J. E. Jones, "Agronomic Studies of Okra and Super Okra Leaf Cotton," Beltwide Cotton Production Research Conferences Proceedings, Las Vegas, Nev., p. 83 to 84 (1977).
(6) L. S. Bird, F. M. Bourland, R. G. Percy, J. E. Hood, and D. L. Bush, "Additional Progress in Developing Okra Leaf, Frego Bract and Glabrous Multi-Adversity Resistant Cottons," Beltwide Cotton Production Research Conferences Proceedings, Atlanta, Ga., p. 107 to 109 (1977).
(7) J. B. Weaver, Jr., "Observations on Bee Activity in Several Genotypes of Cotton," Beltwide Cotton Production Research Conferences Proceedings, Dallas, Tex., p. 76 to 77 (1978).
(8) Jack E. Jones, D. T. Bowman, J. W. Brand, W. D. Caldwell, and D. F. Clower, "Genetic Improvement of Open-Canopy Cottons," Beltwide Cotton Production Research Conferences Proceedings, St. Louis, Mo., p. 72 to 74 (1980).
(9) F. Karami, D. R. Krieg, and J. E. Quisenberry, "Water Relations and Carbon-14 Assimilation of Cotton With Different Leaf Morphology," Crop Science, Vol. 20, p. 421 to 426, July-Aug. 1980.
(10) Jack E. Jones, "The Present State of the Art and Science of Cotton Breeding for Leaf-Morphological Types," Beltwide Cotton Production Research Conferences Proceedings, Las Vegas, Nev., p. 93 to 99 (1982).
The following articles mention the use of narrow leafshaped cotton plants during the production of hybrid cotton:
(1) J. B. Weaver, Jr., and Ralph Graham, "Behavior of Boll Weevils on Cytoplasmic Male-Sterile Cotton in Isolated Plots," Beltwide Cotton Production Research Conferences Proceedings, Atlanta, Ga., p. 100 to 102 (1977).
(2) K. N. Gururajan and K. Srinivasan, "Note on the Use of Okra-Leaf Male-Sterile Line in the Production of Hybrid Cotton," Indian J. Agric. Sci., Vol. 52(1), p. 20 to 21, January 1982.
In Article (1) the use of cytoplasmic male sterile cotton plants having a narrow leaf configuration as a trap crop for insects is mentioned. In Article (2) the possible worth of the okra leaf character with respect to cotton yield is discussed. Each of the articles is silent with respect to an overall commercially practicable process wherein the purity of the hybrid cottonseed product is determined and/or controlled during its production by any means.
It is an object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds which is capable of being readily implemented on a commercial scale.
It is an object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds on an efficient basis wherein the degree of purity of the product readily can be determined on a reliable basis.
It is an object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds on an efficient basis wherein the parent plants optionally can be grown in bulk in the same area and the degree of hybrid purity in the product readily can be determined on a reliable basis.
It is an object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds on an efficient basis wherein sources of non-hybrid contamination in the product readily can be identified as to their likely source.
It is an object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds on an efficient basis wherein in a preferred embodiment contamination in the parental lines readily is identified and is eliminated so as to enhance their purity and the purity of the F.sub.1 hybrid cottonseed product.
It is an object of the present invention to provide an improved process utilizing a cytoplasmic-genetic male sterile system for the production of F.sub.1 hybrid cottonseeds wherein a marker system is utilized for purity control which is readily identifiable, is highly reliable, and is not influenced by the environment.
It is another object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds wherein the required cross-pollination readily can be carried out with the aid of pollen-carrying insects.
It is another object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds wherein an abundant and consistent supply of pollen is provided by the male parent plants.
It is yet another object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds wherein pollen-carrying insects are provided good accessibility to amply exposed flowers of the male parent plants.
It is a further object of the present invention to provide an improved process for forming F.sub.1 hybrid cottonseeds wherein the respective parent plants and the resulting F.sub.1 hybrid plants can be readily identified visually thereby facilitating a more positive identification of field plots.
These and other objects, as well as the scope, nature, and utilization of the claimed process, will be apparent to those skilled in the art from the following detailed description and appended claims.